Method of inserting bearings in bearing recesses



A. H. VALENTINE METHOD OF INSERTING BEARINGS IN BEARING RECESSBS FiledDec.15, 1925 Patented July 3, .1928.

ALBERT H. VALENTINE, OF DAYTON, OHIO, ASSIGNOR TO MORAINE PRODUCTS COM-PATENT OFFICE.

IPANY, OF DAYTON, 0310, A CORPORATION OF OHIO.

mnrnon or mszan'r'me nnanmes IN ermine nncnssns.

Application mm December 15, 1925. Serial No, 75,580.

- This invention relates to' shaft bearings and particularly to bushingsof porous metal which are adapted to be pressed into bearing recesses inmachine frames. g

i Porous bearings arenot easlly machlnable and cannot be brought to adesired size by conventional machining operations such as reaming exceptwith considerable diflicult Because of its porosity, a reductlonof lllSle diameter generally occurs as the bearlng 1s ressed into place. Thisis, in amount, and

or a given wall thickness, generally propor-' tional to the difference.between the inside diameterpf thehole in which the bearing 1s pressedand the outside diameter of the bearing. Due to the necesslty ofallowing some variation in the sizing of the hole lnto wh ch the bearingis pressed, and of the outside and inside diameters, of the hearing,some means must be rovided to eliminate the difference in insi ediameter of the bearingwhen pressed into place.

One of the objects of the present invention is to introduce a bearingbushing into a recess of bearing sup ort in a manner-such that nofurther machining of the bearing is required to adapt it for theshaftWhlCh 1t is intended to support, and such that the bushing will adaptitself .to a recess, the

I diameter of which varies slightly from the prescribed dimension.Further objects and advantages of the resent invention will be apparentfrom the ollowing description, reference be1ng had to the accompanyingdrawings wherem a preferred form of embodiment of the presexit-inventionis clearly shown.

In the drawings: I Figs. 1 and 2 are fra entary views 40 partly insection showing in two positions of operation the apparatus for carrylngout the present invention.

The type of porous metal bearing for which the present invention isparticularly adapted is manufactured by briquetting a mixture ofmetallic powders and void forming ingredients, and sintering the briuettes 7 ing a non-oxidizing atmosphere. The ollowing process is anexample: A mixture of 90 parts by weight of copper, 10 parts t 1n, 6parts, graphite and 2 parts salicylic aeld, 1n a ve finely dividedstate, is bri uetted un-, der high ressure into the form 0 af, bushingsuitable or bearing. The briquetting pres;

sure is approximately 75,000 pounds per are heated in oarbonizing orsintering boxes square inch. A quantity of the, briquettes After removalfrom the sintering boxes the bushings are surfaced and sized byapparatus: including concentric arbor and die members which squeeze thematerial of the bushing into a true cylindrical tubular shape of certaindimensions.- After bein the bushings are'impregnated with In ricant bysoaking them for one and one-half hours in oil havlng a parafiin baseand heated to a temperature of 250 F.

received by bearing recesses of certain .di-

. In" order to adapt the bushings to be" mensions and to receive a shaftof a certain diameter, the outside diameter of the bushmg is initlallygreater than the diameter of the bearing recess by anamount required forpress fitting the bushing into the recess. The inside diameter of thebushing is initially greater than the diameter of the shaft 2 which isto be supported by the bushing.

The difference between the initial inside diameter of the bushing andthe diameter of the bushing after being installed in a. machine frame,is preferably less than the difference between the initial outsidediameter of the bushing and the diameter of the re- 1 i cess whichreceives the bushing. The ratio of the last mentioned diameterdifl'erence to the first mentioned diameter difference will decrease asthe wall thickness of the bearing is increased. For example, for a inchbearing wall, a ratio of .6 has been found sitisfactoryyand for inchwall a ratio 0 5 N u meral 20 in the drawings indicates a bearingsupport having a bearmg recess 21 which is beveled at 23t0 assistentering the bushing within the recess. The bushing 22 is placed uponthe beveled portion 23, and

the reduced end of portion 24 of an arbor i or mandrel is insertedwithin the bushing as shown in Fig. 1. The shoulder 25 of the arborrests against the upper end of the bushing. Relative motion is producedbe tween the bearing support 20 and the assembly of the bushing 22 andarbor .24 so that the bushing will be forced into the space between thearbor 24 and. the bearing support 20 as shown in Fig. 2.- The bearing isslightly reduced in volume by thus forcingbearing recess 21 is 1" indiameter and to receive a bearing v as . being about it into the spacebetween the arbor and the bearing support. Due to the porosity of thebearing material the articles of the hearing are squeezed toget er to acertain extent and take a substantially permanent set so that theinternal diameter of the bushin does not decrease materially after thear or is withdrawn following the operation shown'in Fig. 2. Consequentlythe bearing will not require an machinin to adapt it for receiving a shat journal of certain size.

To illustrate the method of calculating the diameter of the arborportion 24 and the external and internal diameters of the bush-. ing 22,the following example is given: the 1s for a shaft .750 in diameter.Allowing .001" for a running fit between the shaft and the bearing afterbeing installed in diameter of the mandrel portion 24 will be .751.Allowing .003 for a press fitbetween the bushing 22 and the frame 20,the outside diameter of the bushing will be 1.003". The thickness of thebearing wall the inside diameter of the bushing 22 will be initially Thepresentinvention is adapted for use where commercial manufacturing iscarried on. It is apparent that a bearing recess of a certain specifieddiameter will not be absolutely uniform in a substantial quantity ofarts. For example, the tolerance permitted for bearing recess 1" indiameter may be-plus or minus .001. It would still be practical to use abearing bushing of the diameter specified in the example although thebearing recesses might be .999" in diameter. Owmg to the porosity of themetal of which the metal is composed the present invention causes thebushing to adapt itsel to these slight variations in diameter of thebearing recesses which are intended to receive identical bushing parts.From the foregoing description of one example of use of the invention itis apparent that the present method of assembling a bearing in a hole ina machine frame takes up errors in diameter of the bearing; takes uperrors in the receiving hole diameter; provides a cylindrical bearingsurface of slight diametral error; and insures better contact betweenthe bearing outside surface and the surface of the hole in which it isplaced.

Due to its porosity, the bushing does not elongate as it is squeezedbetween the machine frame and the mandrel; therefore there is no slidingof the bearing materiaf relative to the mandrel and 'no burnishing ofthe interior surface of the bushing.

.Hence this process does not cause the pores of the bearing bushing tobe closed so that Y the lubricant within the bearing could not themachine frame.20, the

and the wall of said recess,

flow to the bearing surface. Withdrawal of themandrel after installingthe bushing does not produce appreciable burnishing of its bearinsurface.

Whi e the form of embodiment of the present invention as hereindisclosed constitutes a preferred form, it is to be understood thatother" forms might be adopted, all coming within the scope of the claimswhich follow.. a p

What is claimed is as follows:

1. The method of providing the cylindrical recess of a bearing supportwith a lining of bearing material, which consists in forming a, tubularporous metal bearing having an outside diameter greater than thediameter of the recess for receiving the bearing and having an insidediameter greater than is necessary for proper running-clearance for theshaft journal which is to be received by the'bearing; in assemblin thebearing tube upon a mandrel having a iameter substantially equal to therequired shaft journal; and in producing relative movement between thebearing support and the assembled bearing tube and mandrel in order topress fit the tube within the recess of thebearing support and to reducethe diameter of the bearing tube to that of the mandrel.

2. The method of providing recess of a bearing support with a lining ofbearin material, which consists informing a tubu ar porous metal bearinghaving an outside diameter which exceeds the diameter of the recess byan amount duce a press fit between the bearing tube and the wall of saidrecess, and having an inside diameter exceedin the diameter of therequired shaft journa to be received by the bearing by a fraction lessthan one of the said excess amount required for pressfit; in assemblingthe bearlng ,tube upon a mandrel having adiameter substantiall equal tothe diameter of the required sha t 'ournal; and in producing relativemovement etween the bearing support and the assembled bearing tube andmandrelin order to press fit the tube within th'e' recess of the bearingsupport and to reduce the diameter of the bearing tube to that of themandrel.

3. The method of providing recess of a bearing support bearinmateriahwhich a tubu ar porous metal bearing having an outside diameterwhich exceedsthe diameter of the recess by an amount required to producea press fit between the bearing tube "and having an inside diameterexceeding the diameter of the shaft journal to be received b thebearing, the ratio of the diameter di erence between the initialinternal diameter of the bearing and the diameter of the shaft jouracylindrical with a lining of a cylindrical:

the diameter of required to proconsists in forming i ml to the diameterdifference between the between the bearing support and the asseminitialexternal diameter of the bearing and ,bled bearing tube andma'ndrel inorder to 10 the diameter of the recess being less than {fess fit thetube within the recess of the one and decreasing as the bearing wallthickaring support and to reduce the diameter 5 ness is increased; inassembling the bearing of the bearing tube to that of the mandrel. tubeupon a mandrel having a iameter sub- In testimony whereof I hereto aflixmy stantially e ual to thediameter of said shaft signature. v i journal;an in producing relative movement ALBERT H-'VALENTINE{

